Bob from SWISCO responded:
January 27, 2021
This looks like a 15-180 Balance Shoe, along with a 15-181 Clip. This system uses Series 190 Coil Balances. To know what spring weights needed, look for stamps on the coil balances themselves. If there are none or you are uncertain, obtain the exact weight of the window sash. Give me that exact weight, and we can work out what you need. |